Can Fasting in Ramadan Delay My Period?

Possibly, for some women, but the evidence is thin. The one small study that looked at it found more irregular cycles in the month of Ramadan than in the months before, and it could not show that fasting was the cause. The usual reasons for a late period (stress, a change in eating, weight or sleep) can all arrive together with a month of fasting, so it is hard to pull them apart. If your period is late, rule out pregnancy first.

What the research says

• A cross-sectional study of 80 university students in Iran (Yavangi and colleagues, 2013) asked them to record their periods for three months before, during and after Ramadan. The share with an irregular pattern (periods that were too far apart, too close together or heavier) was 11.3% before Ramadan, 30% during it and 16.3% afterwards.
• Students who fasted more than 15 days had more irregular patterns than those who fasted fewer, but the authors say the second group was only 13 students, which limits how far that comparison can be trusted.
• The authors themselves call for larger studies that measure hormones during fasting. A study like this shows a pattern, not a cause. It cannot say whether fasting, shorter sleep, a heavier schedule or something else changed the cycle.

I did not find a larger study that settles the question, so treat any firm claim you read online, in either direction, with caution.

Other things that can delay a period in the same month

The NHS lists these among the common reasons a period is late or missed, and several of them can overlap with Ramadan:

• Stress. Ongoing stress is one of the causes the NHS names for a late or missed period.
• Weight change or very low weight. Losing weight quickly, being significantly underweight or exercising very intensely can lower the hormones a period depends on.
• Hormonal contraception. The pill, the injection and the hormonal IUS can delay or skip periods, especially in the first months of starting or stopping them. If you took pills to hold your period off for Ramadan, that is a separate and expected cause.
• Pregnancy. It is the most frequent reason a period does not arrive on time, so a home test comes first if there is any chance.
• Medical causes. PCOS and thyroid problems are among the conditions the NHS and Mayo Clinic list. A doctor sorts these out with tests, not a page like this one.

For the general picture, why a period can be late goes through each cause, and how long a cycle should be shows the usual range, so you can see whether a few days is inside it.

When to talk to a doctor

It is worth seeing a doctor if you have missed three periods in a row and you know you are not pregnant, if a late period comes with unexplained weight change, ongoing tiredness, or new hair growth on your face or body, or if bleeding is very heavy or lasts well beyond your usual. If you are fasting and feel dizzy, faint or unwell, that is also a reason to speak to a doctor, whatever your period is doing. This page cannot tell you which cause, if any, applies to you.

What a late period changes for your worship

Nothing about how the blood is judged once it arrives. A period that starts late is still recognised as hayd by its own signs. If it starts during the day while you are fasting, what happens to that fast is covered separately, and the days you miss are made up later: see how to make up fasts missed for your period and how to count the days you owe.

Keep a record of it

Whether Ramadan changes your cycle is easiest to answer from your own dates. Logging when bleeding starts and ends for a few months before and after, in a period tracker built for Muslim women, shows whether this month really is different from your usual. Nisaa does this and is free on the App Store: https://apps.apple.com/app/id6756938661

This page is general information and not medical advice. It cannot diagnose anything. For pain, a missed period you are worried about, or unusual bleeding, speak to a healthcare professional.